In the field of X-ray security inspection, an X-ray vehicle inspection system is comprised of an X-ray imaging sub-system, a scanning control sub-system, an operation inspection sub-system, and a radiation security sub-system. The X-ray imaging sub-system is the core of the whole system, and is comprised of a ray source, a detector, and a data acquisition and control module, to generate X-ray transmitted and/or scattered images. When a container/vehicle to be inspected is scanned, a high-power X-ray pulse is generated by the ray source, is transmitted through goods to be inspected, and is received and converted into an output signal by a high-sensitivity array of detectors. Finally, a series of digital image signals are generated in real time by the data acquisition and control module. When the whole scanning process is completed, a complete image of the vehicle to be inspected is generated automatically by the system.
In a conventional fast inspection system for a container/vehicle, the container is scanned and imaged by using an accelerator as a ray source. In the field of X-ray security inspection, it should be noted that it is beneficial if a driver drives to enable the goods to pass through the static X-ray inspection system. In order to ensure the penetrating power and image quality, the X-ray output by the accelerator has a high dosage rate. However, in most commercial operating environments, when imaging is performed by using a high-dosage X-ray source, a ray dosage accumulated on the driver in the scanning process will reach an unacceptable level. Therefore, as shown in FIG. 1, in order to ensure radiation security of the driver, it needs to avoid scanning the cab. However, a scanned image of the cab and the driver cannot be obtained, and thus there may be a certain security risk. In order to enable the fast inspection system for a container/vehicle to obtain the whole scanned image including the cab, a feasible solution is illustrated in FIG. 2, in which the vehicle head is scanned by using a low-dosage ray, to obtain a scanned image in the premise of ensuring personal security. The compartment is scanned by using a normal-dosage ray.
With respect to the feasible solution illustrated in FIG. 2, there are multiple possible implementations currently. One implementation is that two imaging apparatuses are used as shown in FIG. 3, in which two ray sources (a first ray source and a second ray source) are used to scan the head of the vehicle using a low-dosage ray output by a low-dosage X-ray tube and scan the compartment using a high-dosage ray output by an accelerator. In this implementation, the system structure is complex and the cost is high due to the use of two imaging apparatuses. At the same time, the low-power X-ray tube generated by the low-power X-ray has a poor penetrating power and a non-ideal imaging effect.
Another possible solution of scanning a cab using a low-dosage ray (FIGS. 4A and 4B) is to use an accelerator as a ray source. The accelerator outputs a stable high-dosage ray, and when the cab passes (as shown in FIG. 4A), the ray is blocked by a particular collimating member, to reduce the dosage rate of the X-ray illuminated on the cab, thereby meeting requirements on personal security. When the goods pass (as shown in FIG. 4B), the ray is not blocked by the particular collimating member, to illuminate the goods using a high-dosage ray. Such solution needs a particular mechanical collimating member, which is difficult to control and has a risk of a mechanical fault.